How do they do that?

I use a VOIP (Voice Over Internet Protocol) line as my office phone. The monopoly phone company charged me a ridiculous amount for the privilege of the line because it was business-oriented so I fired them. They still call me relentlessly to tell me they value my business and I get to fire them all over again, and tell them how stupid they are for not getting the hint. That's not what I want to talk to you about, however.

One of the services I have on this line is a "visual voice mail". All the messages that come in are translated using speech recognition technology and sent to me as an email. The technology is not perfect. Some of the translations I get are pretty amusing... except for lately. It's voting season, and I'm getting a round of robo-calls with messages about this politician and that one. Guess what! The transcription from the political messages I get are perfect. That means that somehow, the message has been optimized for text-to speech. How do they do that? Can someone train me to talk to my phone that way?